SPACE-INVARIANT AND ROTATION-INVARIANT IN A GIVEN ANGLE RANGE PATTERN RECOGNITION AND THEIR FILTER DESIGN

Hsu et al have proposed a method of filter design for space-invariant and rotation-invariant digital pattern recognition in terms of circular harmonic expansion. Based on their method, we suggest a new filter design for space-invariant and rotation-invariant in a given angle range pattern recognition system. Although rotation-invariant angle is restricted to centain extents, the ratio of signal to noise might be increased, meanwhile we need not measure the phase factor of correlation function between target and recognition image in order to determine the rotation angle instead of directly measuring the absolute value of correlation function. We also give one simple example to demonstrate this design and compare it withthat suggested by Hsu et al.